It is a bit funny, though, since the quest that gets you the Brothers Sparus unit of spearmen is almost guaranteed to make you fight a (?Giant) Ravenous Harridan if you activate it at a time when you're still using an early game army, and that one is listed as 'weak' (this, of course, is assuming that you choose an option which results in gaining the Brothers Sparus).
I don't know about you guys, but I'd consider a quest which results in a nearly guaranteed fight against a giant spider to be a more challenging quest than one which has a slight chance of a fight against a giant spider, even though Corpse Spiders are more dangerous than Ravenous Harridans.
